Flock Members Research Articles

Cooperative breeding and altruistic behaviour in the mexican jay, Aphelocoma ultramarina

Summary The social organization of the Mexican jay is based on flocks typically of eight to twenty individuals which tend to be evenly dispersed through the appropriate habitat. Most flocks consist of two or more breeding pairs of adults plus a variable number of non-breeding yearlings and adults. The feeding of the young by all the members of the flock was studied in the field under natural conditions by colour banding the flock members. The feeding of the nestlings was shared by all flock members with 38 to 53 per cent of the feeding visits by the parents and the remainder by altruistic jays who were not parents of the nestlings they were feeding. Parents showed a significant preference for feeding their own nestlings as long as they remained in the nest. The feeding of young after they left the nest was also shared by all flock members, with about 26 per cent of the feeding visits by the parents and the remainder by altruistic jays who were not parents of the young they fed. Parents showed no preference for feeding their own fledglings as opposed to the fledglings of other parents.

Ecological Aspects of Some Mixed‐Species Foraging Flocks of Birds

Mixed—species flocks of birds composed of chickadees, titmice, woodpeckers, nuthatches, creepers, kinglets, and wood warblers were studied in several habitats in Louisiana, Maryland, and Maine. Chickadees and titmice usually led these groups. Both the size of the flock and density of birds varied with the habitat. An inverse relation existed between the density of birds in a habitat and the percentage of them that were species participating in flocks. Individuals of species regularly participating in flocks sometimes were found away from them. The tendency for such an individual to be in a flock was inversely related to the density of birds in the habitat. Hostile interactions were infrequent in flocks, being mostly of an intraspecific nature. A dominance hierarchy existed between the different species in flocks. A definite distance was maintained between individuals. As flock size increased the area occupied per individual decreased. The larger flocks were, the faster they usually moved. Each species favored certain parts of the habitat when foraging, though overlap existed between almost all pairs of species. The commonest species (Chickadees, titmice, kinglets) overlapped heavily. Subordinate species foraging in the presence of dominant species changed their areas of foraging, but little or no tendency was seen for subordinates to affect the foraging of dominants. Subordinates might either spread out over alternative foraging areas or concentrate their activities more strongly in a few areas. Most flock members responded markedly to predators; however, few predators were observed during the study. Many of the responses seen were delivered to inappropriate stimuli. Several factors suggest a direct relationship between population density and food supply. Flocking appears to be an effective adaptation to difficult conditions. If a species adjusts its foraging in the presence of another species, possibilities of hostilities should be minimized. Subordinate species usually moved to parts of the habitat to which they were well—adapted. If dominant species are absent, however, opportunism by the subordinate may allow it to take advantage of otherwise unused resources. Dominants may obtain a more predictable portion of the food supply by participating in flocks that if solitary. Constant movement may insure that birds obtain the most readily available food. Large flocks may move rapidly because their individuals are more crowded than those in small flocks. With this restriction either increased speed or more concentrated foraging would be predicted. The low frequency of predators suggests that evasive responses of flock members may have been more advantageous than at present.

ALTERNATIVE ROUTES TO EVOLUTIONARY SUCCESS AS EXHIBITED BY AFRICAN CICHLID FISHES OF THE GENUS TILAPIA AND THE SPECIES FLOCKS OF THE GREAT LAKES.

The cichlid fishes of Africa exhibit two strikingly different patterns of evolution. That members of the genus Tilapia have attained a considerable measure of success by virtue of remaining ecologically generalized while members of the great species flocks which inhabit the major lakes, and which in the majority of cases have been derived from Haplochromis or a Haplochromis-like ancestor, have achieved their success by the diametrically opposite process of super-specialization has already been suggested (Fryer, 1960). The ecological generalization of Tilapia has largely precluded speciation in the great lakes: the diverse super-specializations of many members of the great species flocks have played an important part in their exploitation and sharing of a diversity of habitats and resources and in the ability of many species to co-exist in a single community. During the course of the preparation of a book on these fishes (Fryer and Iles, in press), in which many aspects of their biology will be considered, this difference has been more forcibly brought home to us and we are now able to make a more comprehensive and coherent comparison. As this impinges on several ecological and evolutionary problems related to one of the most spectacular of extant examples of speciation and adaptive radiation it was felt that a brief summary and discussion of certain implications may be of some value.

Productivity of Pullets Influenced by Genetic Selection for Social Dominance Ability and by Stability of Flock Membership ,

INTRODUCTIONSOCIAL stress is usually associated with lowered productivity in chickens. Strange hens introduced into organized flocks are initially harassed and their egg production is depressed (Sanctuary, 1932; Guhl and Allee, 1944; Guhl, 1953; and Morgan and Bonzer, 1959). Low peck-order status also leads to a stressful intra-flock environment for the individual hen and is associated with lower productivity (see Guhl, 1953).Tindell and Craig (1959) confirmed the presence of intra-flock associations between social rank and productivity traits for the early part of the laying year, but found later egg production to be essentially uncorrelated with rank. They also compared 6 diverse genetic strains in intermingled and separate flocks. Inter-strain competition resulted in higher performance levels for the more aggressive strains; whereas, due to their lack of competitive ability, the less aggressive strains matured later, fed less often, had a lower rate of lay and poorer livability as compared to…

Agonistic behaviour influenced by strangeness, crowding and heredity in female domestic fowl ( Gallus gallus)

Effects of strangeness, crowding and heredity on agonistic behaviour in the female domestic fowl were investigated. Strains differentiated for social dominance ability within each of two breeds were used. Significant differences were found between flocks within strain-treatment groups for several criteria of agonistic behaviour, indicating a critical need for adequate replication in such studies. Strangeness and crowding were associated with higher frequencies of social interaction than found in socially undisturbed and uncrowded flocks. Results suggested, however, that individual rates of social interaction were reduced by crowding. Distances between nearest neighbours, compared to distances expected with random distribution, were greater for crowded than for uncrowded flocks. Social interaction frequencies and variances of social tension indexes were greater within socially dominant strains indicating higher levels of social stress. A large breed difference in behavioural response to changing flock membership was found. However, strains within breeds failed to show differential responses in social interaction frequency, when subjected to changing flock membership or crowding.

Structure of flock range in the Long-tailed Tit

1. The home range, structure, distribution and function of the winter flocks of Long-tailed Tit Aegithalos caudatus were studied in three winters during 1965-1968, in a mixedwood of Quercus serrata, Larix leptolepis and Pinus densiflora at footzone of middle Honshu. 2. Using the census methods of observation-mapping, trace-mapping and time-mapping, 243 winter flocks were recorded on the field map, and activity loci, center of activity radii, activity densities, pattern of movement and fighting behaviors were analyzed.3. Winter fiock-size ranged from 3 to 15 (average 7.6) birds and they were most frequently encountered during November and January.4. A flock range consists of the following three components: 1. Basic space. The core of home ringe, with the radius of 200 meters and having high activity density. The 80% of the whole day activity is spent in here, including the places for foraging, bathing, and snow-bathing. 2. Wandering spaces. They radiate from the basic space, two of which may extend as long main wandering courses. They have functional relation to stability of the fiock, 3. Peripheral space. Surrounding area where flock ranges may be overlapped and fightings for defense occur between flocks.5. The form of home range of the flock is oval, the long axis stretching along a small valley and the short axis compressed between ridges. The social stability of a flock is maintained under such topographical factors.6. The range of flock activity can be regarded as flock-territory, since it is defended by the flock as a unit. Exchange of flock members seldom occurs and the flock range do not change through the winter nor through the life of an individual. The defenese between adjoining fiocks is evident.7. In an uniform mixed wood the activity range of a flock is about 0.2km2. It is not subject to the flock-size but to the area of available habitat. The flock never increases to a great size. Thus, the local populations of the Long-tailed Tit are regulated by flock territoriality which has density-dependent function. The size of winter fiocks and their range-size control the population and distribution range of the breeding pairs.

Social inertia and social stability in chickens

Groups of vertebrates that are organized on an hierarchical basis are known to be integrated by the habituation of inter-individual dominance relationships. The learned behaviour as social inertia was demonstrated by contrasting the frequency of agonistic behaviour in a stable flock of hens with one undergoing a regular alternation in flock membership. The stabilizing influence of social inertia was tested by the injection of an androgen which is known to increase the level of aggressiveness and may facilitate social mobility. The treatment increased social tension but relatively few reversals of dominance occurred. Injections of an oestrogen did not alter either aggressiveness or submissiveness. There was a suggestion that cestrogen might affect postures as social signals and thereby indirectly influence social interactions. It was suggested that degrees of stability within a group may introduce variables in experiments on social behaviour, and could mask the effects of hormonal treatments.

Foraging Relationships of Brown‐Headed Nuthatches and Pine Warblers

Foraging behavior and interactions between Brown—headed Nuthatches (Sitta pusilla) and Pine Warblers (Dendroica pinus) were studied in longleaf pine lands of Louisiana during the fall and winter of 1963—64 and 1964—65. Both species frequently were members of flocks that formed around Carolina Chickadees (Parus carolinensis) and Tufted Titmice (P. bicolor). Most contact between the former two species occurred in these flocks. While in flocks, Brown—headed Nuthatches foraged most heavily on the distal parts of limbs and on twigs, Pine Warblers on proximal parts of limbs. When alone, Brown—headed Nuthatches foraged more heavily on trunks and proximal parts of limbs than they did when Pine Warblers. When pine seeds were abundant, Brown—headed Nuthatches fed upon them heavily and regularly ventured to large limbs and trunks to crack seeds, causing increased hostilities with Pine Warblers. Attempts to crack seeds where bark was not sufficiently rough to permit adequate anchoring met with little success. Pine Warblers fed upon pine seeds much less frequently than did Brown—headed Nuthatches. During the height of seed abundance, Brown—headed Nuthatches lingered behind mixed flocks and often became separated from them. More competition for food apparently exists between Brown—headed Nuthatches and Pine Warblers than between either of these species and others. The noticeably different foraging distribution of the two species when together and apart is probably largely the result of the presence or absence of the other. Dividing the habitat in each other's presence avoids fighting over a similar foraging station. Abundant food sources may cause this system to break down.

Winter roost distribution and feeding dispersal of the Grey Starling in Kanto Plain

1. Roost distribution, feeding dispersal and density and behaviour of feeding flocks before roosting flight in the Grey Starling, Sturnus cineraceus, were studied in Kanto Plain from 1953 to 1962. This paper describes the results of some 45 winter observations. The roost distribution will be further iuvestigated.2. In Kanto Plain, extensive feeding range of big Koshigaya roost (about 50, 000 birds) north of Tokyo occupies 30-40km radius circle of the plain. Other smaller roosts are situated outside of this feeding range.3. Daytime (late afternoon observation) feeding flocks usually consisted of several to 30, sometimes 100 birds and each flock was more or less 500m apart. This spacing by small flocks should be a response to the food availability which are minute mud fauna and rather sparcely distributed larger larvae, etc.4. In feeding ground assembly towards evening, up to 300, rarely 500 or exceptionally 1, 000 birds gathered into a flock, the average flock size being 176 birds. Thus an area where a flock of over 150 birds was found could be regarded as a good feeding place. Evening flocks gradually moved always towards the direction of main roost (to which most of the flock members belonged). The distance of this late afternoon movement to final gathering place was usually 1.5-2.0km.5.The density, the economic density, of daytime feeding flocks in the field was 30-500 (average 160) birds per 1km2, therefore 0.3-5.0 (average 1.6) birds per 1 ha, which coincided with previously calculated data. This may suggest that a space of about 1 ha is wanted by one starling.6. Two types of feeding dispersal from a roost were noticed. In type A, the flock size decreased with greater distance along a certain direction and under similar conditions of the feeding environment (see NNW direction in the map). In type B, concentration to a certain feeding area was found. A remarkable concentration was at 40km from the roost which was about the maximum distance of feeding dispersal. On this feeding flight line, the size of feeding flocks decreased with shorter distance from the roost, i. e. greater flock size towards the concentration area. This concentration was possibly due to higher food resources plus good breeding envirnment (old trees with holes).7. The middle area on the B type dispersal line was apparently occupied by a big feeding flock of another roost (confirmed by roosting flight direction). If this were a competitve segregation of feeding grounds by two different roost-flocks, it is a remarkable instance.8. It commonly happens that at the peripheral feeding area, the feeding flocks make a joint flock with birds of other roost or roosts. Thus on starting for roosting flight they take off to different, or to each determined, directions.9. Distribution and observation data at eleven roosts in the study asea (see fig. 1) are described.

SOCIAL BEHAVIOUR OF THE WHITE‐EYE ZOSTEROPS LATERALIS IN WINTER FLOCKS

Summary1. In 1959 and 1960 observations on winter flocks of the White‐eye Zosterops lateralis were made at a feeding station and in an aviary at Dunedin, New Zealand.2. Aggressive behaviour takes different patterns according to the intensity of aggression; ritualized pecking, threat display, incipient attack, combat and chasing are distinguished. Many components of the basic threat posture are similar to those of other passerine species, but “wing fluttering”, presentation of white underwing coverts and the brown colour on the flank, and “beak clattering” seem to be characteristic of the White‐eye. “Wing fluttering” is an incipient attack and often develops into an actual attack when stimulated by identical posturing by an opponent.3. The pecking order found in the captive birds was a peck‐right hierarchy, but triangular relations were also observed when mated birds were involved. Prior residence was effective for a short period only and the despot in the prior occupants could be defeated by an aggressive intruder.4. 710 birds were colour‐ringed at the feeding station, 306 returned and 204 were observed in aggressive encounters. The analysis of these encounters showed that in natural flocks dominant birds are engaged in aggressive encounters more frequently than subordinate birds, that dominants fight more often with birds of higher ranks, and that subordinates avoid encounters with aggressive birds.5. A complex peck‐right hierarchy was found among members of different flocks visiting the feeding station. It is suggested that aggressive behaviour serves to establish and maintain the social hierarchy among individuals coming into contact over various objects. In crowded conditions severe fighting frequently takes place and the right of prior residence may be challenged constantly.6. The importance of ecological implications of flocking and aggressive behaviour in the White‐eye population in New Zealand is discussed.

The flocking behaviour of wintering Brown-eared Bulbuls and their spring departure

Local wintering flock of the Brown-eared Bulbul, Hypsipetes amaurotis (Temminck), is a stationary closed being resident within a certain wintering area without change of the flock members. But, the flock consisted of opened subflocks, the groups within a main flock, with free interchange of members.In spring, the wintering flock broke up by moving-out of members and in this season, the moving groups of a local flock may pass and/or temporarily join other local flock, and the latter may leave with the passing flock. This may be determined by coincidence of birds' physiological condition.Most birds of the wintering flock disappeared at the same time, but a few birds remained over a month. The disappearance of the main flock fairly well coincided with the end of abundant fruits of a tree, and remaining few individuals appeared to have suffered from lack of enough food. Thus, they were observed eating (rather unwillingly) the buds of the leaves of Viburnum awabucki K. Koch.) The flower of Cammellia is a favourite food (both nectar and eating) available until late in the season, but it is not the main food.The disappearance of the main flock (March 2) coincided with the general increase of temperature to above 15°C. and the remaining few birds disappeared (April 16) with the rise of temperature to over 20°C., when passing flocks were observed most frequently (Fig. 2). This difference in migration temperature might indicate the mixture of northern and relatively southern breeding individuals within a wintering flock.Marked restlessness in behaviour was observed in spring among birds of a flock. The individuals in such state flatter at random in an excited hovering flight near high branches, with frequent breaks by short perchings. Also, two birds often chased with each other excitedly, but this seemed not to be a courtship flight.

The spread of genes by natural and artificial selection in closed poultry flock

The pedigrees of birds in a poultry flock under artificial selection were analysed to trace the spread of genes from original flock members. The changes in gene percentage from generation to generation were separated into parts attributed to chance, natural and artificial selection. The changes due to artificial selection were related to various production characters. The spread of the male's genes was 70% determined by a progeny test which also 25% determined the spread of genes of birds mated to him. The progeny test of the female did not contribute equally to determination of the gene spread. This was attributed to lesser accuracy of the female progeny test and less complete determination of spread of genes by value of genotype. Despite avoidance of sib matings, inbrecding has increased 2% per generation. Evidence that natural selection was opposing artificial selection was suggestive but inconclusive. It was suggested that assortative mating would increase the determination of gene spread by genotypic value. This was considered worth testing.

Effect of Antibiotic Agents upon Experimental Ascaridia galli Infections in Chickens

TWO main avenues of investigation are employed by agricultural parasitologists to aid domestic animals in attaining maximum efficient production. The first of these, medication, is directed most properly at infections carried by members of the breeding flocks because their infections are reservoirs for the exposure of new generations of animals. Secondarily, medicated feeds have come into use to protect against and minimize the effects of parasitic infections in animals constituting an individual generation. Control of parasitism appears to rest upon proper and efficient use of medication. The other basis of investigation is in connection with determining relationships of nutrient materials in the diet of animals to the ability of the animals to withstand, or tolerate, effects of infection. Both types of investigation are based upon modern and efficient methods of sanitation and management.While present antibiotic agents perhaps have been developed primarily to combat infections caused by bacteria, the later .

Experimental Modification of Breeding Cycles in Goats

ECENT ECENT studies on the modification of sexual or breeding cycles of field mice, ferrets, raccoons, guinea pigs, ground squirrels, cottontail rabbits, and other mammals with limited annual breeding periods confined to the seasons of long or lengthening days, shows that some, but not all of them, are sexually photoperiodic. Within limits, the breeding cycles of the sexually photoperiodic ones can be modified at will by altering experimentally the duration of their daily periods of exposure to light (Bissonnette, 1936, 1938; Marshall, 1936, 1937; Wells and Zalesky, 1940; and others cited by them). Some animals, however, breed not in the long-day seasons but in those of short or shortening day. Brook trout, sheep, deer, and goats are some of these. The change-over of the breeding seasons of the three last-named species when they are transferred to the Southern Hemisphere (Marshall, 1937), and the success of Hoover and Hubbard (1937) in causing a December-spawning strain of brook trout to spawn and produce viable, wellgrowing, healthy offspring in August, suggested that similar success might be obtained with goats. Such control and shifting of breeding cycles will make possible the freshening of some members of large flocks throughout the year. It would enable breeders to bridge the hiatus which normally occurs from late August to late January, because goats have a gestation period of 21-22 weeks and fail to breed between early April and September.